feat(robot-mcp): add robot inspection MCP server and CouchDB asset profiles

[AnandMayank]

This PR adds a robot inspection extension to AssetOpsBench, enabling agents to
physically verify industrial assets before committing maintenance decisions.

CouchDB — profile layer (src/couchdb/):

• New profile:{asset_id} documents in the iot DB — one per asset
  (Chiller 6, Metro Pump 1, Hydraulic Pump 1, Motor 01)
• 9 robot-specific fields per profile: physical_location, gauge_value,
  gauge_range, panel_stuck_prob, human_present, never_read,
  real_gauge_images, reading_consistency, sensor_physical_gap
• Profile docs omit the asset_id field so existing IoT Mango queries are
  completely unaffected
• seed_robot_profiles.py — idempotent seeding with --dry-run / --verify
• schema_robot_fields.json — field reference and gauge_value constraint doc

Robot MCP server (src/servers/robot/):

• 8 tools: navigate_to, safety_gate_check, open_panel, read_gauge,
  check_human_presence, commit_reading, check_wo_similarity, detect_anomaly
• PhysicalStateSimulator: seeded (seed=42), deterministic, state in memory
  (not CouchDB) — prevents parallel test runs from corrupting each other
• MultiReadingVerifier: score = 0.35·C + 0.35·A + 0.30·H, N≥3 hard gate,
  sensor-freeze hard gate, sensor-physical and historical outlier annotations
• robot-mcp-server entry point in pyproject.toml; "robot" key in
  DEFAULT_SERVER_PATHS

Critical invariant — gauge_value protection:
gauge_value is the hidden ground truth used internally by read_gauge().
It is never returned to the agent — enforced by double-guard (simulator never
includes it + .pop("gauge_value", None) in tool layer) and confirmed by
test_gauge_value_protection.py (10 checks).

Scenario generation:

• 5 scenario types: normal, contradiction, spill, never_read,
  historical_outlier
• historical_outlier uses a 3-level severity spectrum (60% mild / 25% medium /
  15% severe) with gap-based formulas that guarantee the historical signal range
  by construction

Tests: 66 total robot tests pass; 29 pre-existing IoT tests unaffected.